DETROIT -- A Swiss hospital had disclosed that it treated former Fiat Chrysler CEO Sergio Marchionne for a "serious illness" for more than a year before he died Wednesday at age 66.

The auto world was shocked by the colorful executive's death, which had appeared to have come suddenly. Fiat Chrysler only disclosed Saturday that Marchionne was seriously ill and at that time named his successor, Jeep brand chief Mike Manley.

Until then, it was known only that Marchionne had had complications after shoulder surgery last month.

"To prevent further speculation: Mr. Sergio Marchionne was a patient at USZ. Due to serious illness, he had been the recipient of recurring treatment for more than a year," the hospital said. "Although all the options offered by cutting-edge medicine were utilized, Mr. Marchionne unfortunately passed away. We deeply regret his death and would like to express our sincere condolences to his family."

The Italian website Lettera43.it, citing anonymous sources, said in a post Wednesday that Marchionne suffered an embolism during surgery and lapsed into a coma — and that his health was worse than had been reported when he entered University Hospital in late June.

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Fiat Chrysler said it "is not in a position to comment on statements made by University Hospital Zurich. Due to medical privacy, the company had no knowledge of the facts relating to Mr. Marchionne’s health."

Fiat Chrysler said it had been told that Marchionne had undergone shoulder surgery.

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Chrysler Group Chairman and CEO Sergio Marchionne smiles after a news conference at the Mack I Engine Plant in Detroit, Thursday, Nov. 15, 2012. Chrysler plans to add 1,250 jobs at three Detroit-area factories in the near future. Paul Sancya, AP

Fiat CEO Sergio Marchionne gestures next to the new Bravo car during its presentation to the press in Rome, Wednesday, Jan. 31, 2007. The Bravo, unveiled Tuesday evening to much fanfare, is the model that Fiat hopes will help solidify the company's turnaround and represent a credible entry into the mid-size sedan C class populated by the VW Golf, the Peugeot 7, the GM Astra and Ford Focus. GREGORIO BORGIA, ASSOCIATED PRESS

Chrysler Group CEO Sergio Marchionne addresses workers and guests at the Sterling Heights Assembly Plant in Sterling Heights, Mich., Tuesday, May 24, 2011. Marchionne acknowledged and expressed gratitude for the financial support from the U.S. and Canadian governments. Carlos Osorio, AP

Sergio Marchionne, Chairman and CEO Chrysler Group LLC, announces that Chrysler will add a third shift to begin production of the 2013 Dodge Dart, Thursday, Feb. 2, 2012 at the Belvidere, Ill., plant. Charles Rex Arbogast, AP

Sergio Marchionne, Chief Executive Officer, Fiat Chrysler Automobiles (left) and John Elkann, Chairman, Fiat Chrysler Automobiles ring the Closing Bell on the floor of the New York Stock Exchange (NYSE) on October 13, 2014 in New York City. The two automotive executives rang the bell to celebrate the company's October 13 listing on the New York Stock Exchange. Spencer Platt, Getty Images

After receiving an honorary Doctor of Engineering Degree, Sergio Marchionne, chairman and CEO of Chrysler and Fiat gives the keynote address at Michigan State University Commencement Saturday, Dec. 14, 2013 in East Lansing. Robert Killips, Lansing State Journal

US President Donald J. Trump (C) is flanked by CEO of General Motors, Mary Barra (L), and CEO of Fiat Chrysler Automobiles, Sergio Marchionne (r), during a meeting with automobile industry leaders in the Roosevelt Room of the White House in Washington, DC, USA, 24 January 2017. SHAWN THEW, EPA

Sergio Marchionne, CEO of Fiat Chrysler Automobiles, and Ralph Gilles, FCA Global Head of Design, talk after the debut of the new 2019 Jeep Cherokee at the 2018 North American International Auto Show January 16, 2018 in Detroit, Michigan. Bill Pugliano, Getty Images

(L to R) John Elkann, chairman of Fiat Chrysler Automobiles and Sergio Marchionne the CEO of Fiat Chrysler Automobiles laugh and talk with others before the unveiling of the 2017 Chrysler Pacifica during the 2016 North American International Auto Show held at Cobo Center in downtown Detroit on Monday, Jan. 11, 2017. Eric Seals, Detroit Free Press

Fiat Chrysler CEO Sergio Marchionne, left, shakes hands with UAW President Dennis Williams, during an event to mark the ceremonial beginning of its contract talks at the UAW-Chrysler National Training Center in Detroit on Tuesday, July 14, 2015. Kimberly P. Mitchell,Detroit Free Press

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Then, "On Friday, July 20, the company was made aware with no detail by Mr. Marchionne’s family of the serious deterioration in Mr. Marchionne's condition and that as a result he would be unable to return to work. The company promptly took and announced the appropriate action the following day."

Marchionne’s family confirmed by email to Bloomberg that the companies Marchionne ran — Fiat Chrysler, Ferrari and tractor maker CNH Industrial — weren’t told of his health condition until late last week when they were notified he wouldn’t return to work.

Lettera43 reported that Marchionne "had been diagnosed some time ago with a rather invasive shoulder cancer." An earlier post described it as a soft-tissue sarcoma.